The present invention relates to a D.C. motor drive system with two quadrant motoring regenerating operation.
It is known in the art of machine drives that some loads tend to develop their own positive torque which creates a speed-up influence which is disadvantageous from the standpoint of maintaining as constant a speed as possible. A similar problem may occur when a lower motor speed is set by a controller relative to the then speed of the motor. It is well known in the existing technology to provide mechanical or electrical means to deal with this problem such as through heat dissipation using a dynamic braking resistor, through the use of an auxiliary generator system or other means. With existing solutions there are heating problems and many times the requirement of an excessively large or costly motor. In accordance with the present invention more torque and horsepower are developed for a given motor size. The form factor is quite close to unity which thus prolongs brush life. Furthermore, with the control of this invention 120 Hertz discontinuities are removed.
Accordingly, an object of the present invention is to provide motor speed control that is of improved type not having the drawbacks presented by the prior art techniques.